Alloy Leaching ORP Control for Nickel-Cobalt Separation
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Solution Overview
Problem
Current methods for recovering nickel and cobalt from discarded lithium ion batteries face challenges such as high energy consumption, incomplete separation, and environmental concerns, particularly in separating copper and nickel due to their uniform melting properties and the formation of toxic compounds.
Innovation Solution
A method involving a leaching treatment with an acid solution and controlling the oxidation-reduction potential (ORP) to selectively leach nickel and cobalt from alloys, using a sulfurizing agent and intermittently reducing the ORP to remove the oxide film, followed by reduction and oxidation-neutralization steps to achieve efficient separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If dry treatment (pyrometallurgy) is used to recover valuable metals from discarded LIB, then various impurities can be separated together and slag has chemically stable properties, but valuable components particularly cobalt are distributed to slag causing recovery losses
Solution Approach 1:
The patent changes the chemical parameters of the leaching solution by controlling oxidation-reduction potential (ORP) and pH to selectively leach nickel and cobalt while leaving copper in the residue. This avoids the energy-intensive high-temperature heating of dry treatment while preventing cobalt loss to slag through selective dissolution based on electrochemical potential differences.
Solution Approach 2:
The patent replaces the thermal-mechanical separation process (pyrometallurgy requiring high-temperature melting and slag formation) with a chemical leaching process using acid solutions and redox reactions. This substitution eliminates the need for high-temperature heating while achieving selective separation of valuable metals.
2Manufacturing precision
If dry treatment is used to obtain alloy containing valuable components, then separation of impurities is achieved, but further separation and refining of each component is required
Solution Approach 1:
The patent segments the separation process into distinct stages: first selectively leaching nickel and cobalt into solution while leaving copper in residue, then further separating nickel and cobalt through controlled precipitation or solvent extraction. This segmented approach achieves high purity without requiring complex multi-step refining of a mixed alloy.
Solution Approach 2:
The patent uses an acid leaching solution as an intermediary medium to selectively dissolve nickel and cobalt from the alloy. This intermediary chemical process enables direct separation of valuable components in high-purity form, eliminating the need for subsequent alloy refinement operations.
3Manufacturing precision
If copper and nickel are separated by slowly cooling molten state, then separation is achieved, but copper and nickel cannot be separated as they uniformly melt and only form layered mixture
Solution Approach 1:
The patent replaces the thermal separation method (slow cooling of molten alloy) with a chemical leaching method using acid solutions. This substitution allows separation at lower temperatures by exploiting differences in electrochemical reactivity and solubility, achieving complete separation rather than just layered mixing.
Solution Approach 2:
The patent changes the separation mechanism from physical (based on melting point differences and density stratification during cooling) to chemical (based on differential dissolution rates and electrochemical potentials in acid solution). This parameter change enables effective separation of copper and nickel without high-temperature melting.
4Manufacturing precision
If nickel is disproportionated using carbon monoxide gas, then nickel is volatilized and separated from copper and cobalt, but safety cannot be secured due to toxic CO gas
Solution Approach 1:
The patent replaces the use of toxic carbon monoxide gas with safer acid leaching solutions and controlled redox reactions. This substitution maintains effective nickel separation while eliminating the safety hazards associated with handling and volatilizing toxic gases, achieving the same separation purity through chemically safer means.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method allows for the selective leaching of nickel and cobalt from alloys, effectively separating them from copper, reducing recovery losses, and minimizing environmental impact by controlling the ORP and using sulfurizing agents.
Implementation Method 1
a leaching step of adding an acid solution to an alloy including nickel and/or cobalt and copper in a state in which a sulfurizing agent coexists, and performing a leaching treatment
Implementation Method 2
performing a leaching treatment while controlling an oxidation-reduction potential (the reference electrode is a silver/silver chloride electrode) to 100 mV or more and less than 250 mV
Implementation Method 3
an operation for temporarily reducing the oxidation-reduction potential to −100 mV or less is performed in the leaching treatment
Implementation Method 4
adding an acid solution to the alloy in a state in which a sulfurizing agent coexists
Data Source
AI summary
A method is provided which enables selectively leaching nickel and/or cobalt from an alloy that contains copper and nickel and/or cobalt in a waste lithium ion battery.This alloy processing method involves obtaining a solution that contains nickel and/or cobalt from an alloy that contains copper and nickel and/or cobalt, wherein the alloy processing method involves a leaching step for adding an acid solution to the alloy in a state in which a sulfurizing agent is also present, and obtaining a leachate and a leaching residue by performing leaching processing while controlling the redox potential (the reference electrode being a silver/silver chloride electrode) to at least 100 mV and less than 250 mV. In the leaching processing in the leaching step, an operation is performed that temporarily decreases the redox potential to less than or equal to −100 mV.